[img]http://i.imgur.com/x0vKMVN.jpg[/img]
Somehow my filament reel got tangled! The extruder couldn't pull any more filament through, so my printer was extruding nothing for a few minutes until I noticed.
I'm guessing that when I put the reel away, I must have accidentally poked the end through another loop, leaving it to tangle for next time.
Lesson learned
